1. Field of the Invention
This invention relates to a method for manufacturing a thin film magnetic head usable for a magnetic recording and reproducing drive device such as a magnetic disk drive device.
2. Related Art Statement
For realizing a high recording density in a magnetic disk using a thin film magnetic head, it is required that data amount (data density) to be restored in the unit area of the magnetic disk is enhanced. The surface recording density depends on performance of a recording element, and can be enhanced by shortening the gap length between the recording poles of the recording element.
The surface recording density can be also enhanced by increasing the track number to be recorded in the magnetic disk. The track number recordable in the magnetic disk is normally represented as xe2x80x9cTPI (track per inch)xe2x80x9d. The TPI performance of the recording element can be enhanced by downsizing the recording head to determine the width of the data track. The size of the recording head is normally known as a track width.
However, the shortening of the gap length between the recording poles and the narrowing of the track width decrease the magnetic flux in between the recording poles, resulting in the degradation of the overwrite performance. Therefore, in view of recording performance, the shortening of the gap length and the narrowing of the track width can not employed for a high density recording magnetic disk having a high coercivity Hc.
To solve this problem, the recording pole structure in which in a recording pole portion, a magnetic film having a high saturated magnetic flux density (a first magnetic film) is provided adjacent to a gap film and a second magnetic film having a smaller saturated magnetic flux density than the first magnetic film is provided on the first magnetic film is suggested and practically used. For example, the specification of U.S. Pat. No. 5,606,478 discloses that the part of the recording pole portion adjacent to the gap film is made of a magnetic material having a higher saturated magnetic flux, for example Ni55Fe45, than the magnetic material having a NiFe composition which is usually used for the pole portion of the above thin film magnetic head. However, the Ni55Fe45 material has only 1.4T to 1.5T, so that the recording performance is restricted.
In addition, the specification of Kokai Publication Kokai Hei 5-73839 (JP A 5-73839) discloses that an underfilm to plate a bottom magnetic core and a top magnetic core is made of a magnetic material having a higher saturated magnetic flux density than the magnetic materials constituting the bottom magnetic core and the top magnetic core.
In defining the track width of the recording pole portion using the above means in those related documents, the underfilm made of the magnetic film having the higher saturated magnetic flux density has to be etched by milling, etc. In the etching process, the part of the magnetic material constituting the underfilm is re-stuck on the side surfaces, etc. of the pole portion, resulting in the increase of the track width. This means the opposite result to the narrowing of the track width. Moreover, the re-stuck portion of the pole portion usually has inferior magnetic characteristics, so that the electromagnetic conversion characteristics of the pole portion is deteriorated.
If the underfilm is thinner, the re-sticking can be reduced. However, the thinner underfilm can not realize the essential object of enhancing the recording performance by making the underfilm of the magnetic material having a high saturated magnetic flux density. The above related documents do not disclose the means for solving the above problems due to the re-sticking.
It is an object of the present invention to provide a method for manufacturing a thin film magnetic head in which the re-sticking is almost never brought about if a magnetic film, provided adjacent to a write gap film, having a high saturated magnetic flux density is thicker.
It is another object of the present invention to provide a method for manufacturing a thin film magnetic head having a recording pole structure of high recording performance.
For accomplishing the objects, this invention is directed to a method for manufacturing a thin film magnetic head including a recording pole portion. The recording pole portion includes a first pole portion, a gap film adjacent to the first pole portion and a second pole portion adjacent to the gap film. The second pole portion has a first magnetic film and a second magnetic film. The first magnetic film has a higher saturated magnetic flux density than the second magnetic film and is provided adjacent to the gap film, and the second magnetic film is provided adjacent to the first magnetic film.
In manufacturing the above thin film magnetic head, the manufacturing method of the present invention has the steps of forming, on the gap film, the first magnetic film in a primary pattern after forming the first pole portion and the gap film and of forming the second magnetic film by a frame-plating method.
In the above steps, the primary pattern is formed so that its size can be larger than the definitive pattern of the first magnetic film and its edges can be located within frames to be used in the frame-plating method.
According to the manufacturing method, the etching of the first magnetic film in the definitive pattern by dry-etching such as RIE or milling using the second magnetic film as a mask can remove the re-stuck magnetic material of the first magnetic film from the both side surfaces of the first and second magnetic films in the track direction. After the first magnetic film is etched in the definitive pattern, the re-sticking does not occur. Consequently, even if the first magnetic film having a high saturated magnetic flux density is thicker, the re-sticking almost never occur.
Moreover, this invention discloses two modes of the manufacturing method concretely.
The first mode-manufacturing method includes the following steps.
First of all, a magnetic film to be the first magnetic film is formed on the gap film. Then, a mask having a pattern larger than the definitive pattern of the first magnetic film is formed on the magnetic film. The part of the magnetic film uncovered with the mask is removed to form the first magnetic film having the primary pattern.
Subsequently, an plate underfilm is formed on the first magnetic film having the primary pattern and the gap film. Then, frames for frame-plating the second magnetic film is formed on the plate underfilm. The frames are separated on the first magnetic film in the parallel track direction thereto and cover the both edges of the first magnetic film and the gap film around the both edges in the track direction.
Subsequently, a plate film to be the second magnetic film is stuck on the part of the plate underfilm uncovered with the frame, and thereafter, the frame is removed.
Next, the part of the plate underfilm which is exposed followed by the removing of the frame is removed. Since the plate underfilm is extremely thin, the material constituting the plate underfilm is not stuck on the both side surfaces of the first and second magnetic films in the track direction even if the plate underfilm is removed by dry-etching such as milling or reactive ion etching (hereinafter, abbreviated to xe2x80x9cRIExe2x80x9d). Moreover, since the first magnetic film is patterned to have the primary pattern, in removing the plate underfilm, only the plate underfilm has to be etched and the first magnetic film dose not have to. Therefore, the above conventional problems due to the re-sticking of magnetic material constituting the first magnetic film can be prevented.
Furthermore, although the second magnetic film is exposed to the dry-etching in the above removing process of the plate underfilm by the dry-etching, the extremely thin plate underfilm can repress the reduction of the second magnetic film to the utmost. Therefore, the thin film magnetic head having the recording pole structure with a high recording performance can be provided.
Then, the plate underfilm is removed and a mask to cover the first and second magnetic films is formed. The parts of the plate film and the plate underfilm uncovered with the mask are removed. The plate film and the plate underfilm may be removed by RIE, milling, chemical etching or the like. Since the first and second magnetic films are covered with the mask, they are not reduced.
The mask is removed and the first magnetic film is patterned in the definitive pattern. Since the first magnetic film has the primary pattern which is larger than the definitive pattern and of which edges are located within the frame to be used in the frame-plating method, the etching of the first magnetic film can remove the re-stuck magnetic material of the first magnetic film from the both side surfaces of the first and second magnetic films in the track direction in patterning the first magnetic film in the definitive pattern by dry-etching such as RIE or milling.
Moreover, at the time of patterning the first magnetic film, the plate film to be the second magnetic film and the plate underfilm are already removed around the first magnetic film. Therefore, if the magnetic material of the first magnetic film is re-stuck in the both side surfaces of the first and second magnetic films in the track direction due to the patterning of the first magnetic film by dry-etching such as RIE or milling, the re-stuck magnetic material can be removed from the both sides of the first and second magnetic films having no obstacles in the track direction. Therefore, if the first magnetic film having a high saturated magnetic flux density provided adjacent to the gap film is thick, the re-sticking almost never occur.
Furthermore, since the reduction of the second magnetic film can be repressed to the utmost through the whole process, the thin film magnetic head having the recording pole structure having a high recording performance can be provided.
The second mode-manufacturing method includes the following steps.
First of all, a non-magnetic film is formed entirely on a gap film. Then, a hollowed hole having a pattern corresponding to the primary pattern of the first magnetic film is formed in the non-magnetic film.
Subsequently, a magnetic film to be the first magnetic film is formed on the non-magnetic film and the part of the gap film exposed to the bottom of the hollowed hole.
Next, the first magnetic film is flattened so that the surface of the part of the first magnetic film in the hollowed hole can have the substantially same level as that of the non-magnetic film to form the primarily patterned first magnetic film.
Thereafter, the similar steps to the first mode-manufacturing method are carried out. As a result, the similar operation and effect to the first mode-manufacturing method can be obtained and the objects of the present invention can be achieved.